The unique correspondence of the item response function and item category response functions in polytomously scored item response models

Andrich, D. (1978). A rating formulation for ordered response categories.Psychometrika, 43, 516–573.

Bock, R. D. (1972). Estimating item parameters and latent ability when the responses are scored in two or more nominal categories.Psychometrika, 37, 29–51.

Chang, H., Mazzeo, J., & Roussos, L. (1993, April).Extension of Shealy-Stout's DIF procedures to polytomously scored items. Paper presented at the 1993 NCME meeting, Atlanta, GA.

Masters, G. N. (1982). A Rasch model for partial credit scoring.Psychometrika, 47, 149–174.

Muraki, E. (1992). A generalized partial credit model: application of an EM algorithm.Applied Psychological Measurement, 16, 159–176.

Samejima, F. (1969). Estimation of latent ability using a response pattern of graded scores.Psychometrika Monograph No. 17, 34 (4, Pt. 2).

Samejima, F. (1972). A general model for free-response data.Psychometrika Monograph No. 18, 37 (1, Pt. 2).

Shealy, R., & Stout, W. (1993). A model-based standardization approach that separates true bias/DIF from group ability differences and detects test bias/DTF as well as item bias/DIF.Psychometrika, 58, 159–194.

Thissen, D., & Steinberg, L. (1986). A taxonomy of item response models.Psychometrika, 51, 567–577.

Wilson, M., & Masters, G. N. (1993). The partial credit model and null categories.Psychometrika, 58, 87–99.

Wright, B., & Masters, G. N. (1982).Rating scale analysis. Chicago: MESA Press.